Use a and d to rotate the first arrow and right and left arrow keys to rotate the second one. Press space to draw. Use turbo mode (shift-click green flag to activate it) for faster drawing. After turning on turbo, you can press c to enter a makeshift "constantly redraw" mode. You can adjust the arrows while the fractal is being drawn in this mode, but the fractal is rougher. Press space to end it.
This is like the simplest type of fractal there is. Should have used vector sprites to create circles that are actually round, but too lazy to bother with new features.